Check state argument type before attempting conversion (#1956)

Author: Greg Brooks

can/util.py

@@ -249,7 +249,7 @@ def _create_bus_config(config: dict[str, Any]) -> typechecking.BusConfig:
     if "fd" in config:
         config["fd"] = config["fd"] not in (0, False)
 
-    if "state" in config:
+    if "state" in config and not isinstance(config["state"], can.BusState):
         try:
             config["state"] = can.BusState[config["state"]]
         except KeyError as e: